Android应用Google Drive API指定账号认证及Google邮箱密码认证问询

Great question! Let's walk through how to handle this scenario—since you want to skip the account picker and authenticate a specific Google account directly for Drive API access, there are a few key steps and important caveats to keep in mind.

Key Prerequisite #

First, a critical limitation: you can only authenticate accounts that are already added to the user's Android device. Google's security policies prevent apps from programmatically logging into an account that isn't already present on the device (you can't hardcode credentials or force-login an account the user hasn't added via system settings). So your target account must be in the user's "Settings > Accounts" list beforehand.

Step-by-Step Implementation #

1. Configure Google Sign-In with the Target Account #

When building your GoogleSignInOptions, use the setAccount() method to specify the email address of the account you want to authenticate. This tells the Sign-In client to prioritize this account for silent authentication.

// Kotlin example
val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
    .requestScopes(DriveScopes.DRIVE_FILE) // Adjust scope based on your needs
    .setAccount("your-target-account@example.com") // Replace with your target account email
    .build()

val googleSignInClient = GoogleSignIn.getClient(this, gso)

2. Attempt Silent Authentication #

Instead of launching the account picker intent directly, use silentSignIn() to try authenticating without user interaction. This will succeed only if:

• The target account is on the device
• The account has previously granted your app the requested scopes

googleSignInClient.silentSignIn()
    .addOnCompleteListener(this) { task ->
        if (task.isSuccessful) {
            // Authentication succeeded—get the account and initialize Drive service
            val signedInAccount = task.result
            val credential = GoogleAccountCredential.usingOAuth2(
                this, listOf(DriveScopes.DRIVE_FILE)
            ).setSelectedAccount(signedInAccount.account)

            val driveService = Drive.Builder(
                AndroidHttp.newCompatibleTransport(),
                GsonFactory.getDefaultInstance(),
                credential
            ).setApplicationName("Your App Name").build()

            // Now use driveService to access files from the target account
        } else {
            // Silent auth failed (account not on device, or no prior authorization)
            // Fallback to showing the account picker as a last resort
            task.result?.resolution?.let { resolution ->
                startIntentSenderForResult(
                    resolution.intentSender,
                    RC_SIGN_IN, // Define this constant (e.g., 1001)
                    null, 0, 0, 0, null
                )
            }
        }
    }

3. Handle the Fallback (If Needed) #

If silent authentication fails, you'll have to let the user select an account (since you can't force an account that's not present or authorized). In the onActivityResult (or registerForActivityResult for newer Android versions), you can process the selected account normally.

Critical Notes #

• Security & Policy Compliance: Google prohibits apps from bypassing user consent to access accounts. This method only works for accounts the user has already added and authorized—you can't automate login for an account the user hasn't explicitly added to their device.
• Service Accounts (Alternative): If you need to access a central service account (not a user's personal account), consider using a Google Service Account with domain-wide delegation (if you're in a G Suite/Google Workspace environment). This lets you authenticate as the service account without relying on user accounts on the device.
• Scope Consistency: Ensure the scopes you request in GoogleSignInOptions match what you use when initializing the Drive service. Mismatched scopes will cause authentication failures.

内容的提问来源于stack exchange，提问作者Double_M